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INSTALLATION CONSIDERATIONS:
There are many variables to consider when choosing the proper size air
blower for your spa or hot tub. These include: water depth, the number and
size of air holes, distance of blower from spa, number of 90 and 45
degree turns, and the size of the supply line. Together these variables create
back pressure on the blower as measured in inches of water column (inches
H2O). Compare your calculations with the chart below to determine
the best size blower for your spa.
u
Measure maximum height of water from ground to top of spa.
u
For each 10 feet of 1.5" supply pipe, add 3/4" (inch) of water pressure.
u
For each 10 feet of 2.0’ supply pipe, add 1” (inch) of water pressure.
u
For each 90 degree turn, add 1/2" (inch) of water pressure.
Example:
An 8 ft. portable spa with a water depth of 38 inches with 6 feet of 1.5” supply
line to the air manifold with 2 - 90 degree turns.
Calculation of total water pressure is as follows:
1. Water height in spa = 38"
2. 6 feet of supply line = .45”
3. 2 - 90 degree turns = 1.0”
Total water height is 39.45" of water pressure (inches H2O).
This spa would require a 1.0 hp blower – Refer to the chart below.
BLOWER SIZE/MODEL
VOLTS
AMPS
INCHES OF WATER
SILENT AIRE 600 (1.0HP)
120/240
4.8/2.25
UP TO 40"
SILENT AIRE 800 (1.5HP)
120/240
7.0/3.6
UP TO 50"
BLOWER SIZING:
The number of air injectors or holes in the air channel determine the size of
blower required. For example a 1.0hp blower should have a total hole area of
approx. .85 square inches and a 1.5hp should have approx. 1.2 square
inches. Use the table below to determine the correct blower size.
Hole Diameter (Sq. Inches)
Hole Area (Sq. Inches)
1/8"
0.0123
3/16"
0.0277
1/4"
0.0491
